Electrophotographic sensitizers

ABSTRACT

COMPOUNDS HAVING THE STRUCTURE   AR1-N(-AR2)-1,4-PHENYLENE-(C(-1,4-PHENYLENE-N(-AR1)-AR2)   =(2,5-CYCLOHEXADIENE-1,4-DIYLIDENE)=N(+)(-AR2)-AR1)N-H   X(-)   ARE SENSITIZERS FOR PHOTOCONDUCTORS IN ELECTROPHOTOGRAPHIC ELEMENTS.

United States Patent Ofice 3,705,913 Patented Dec. 12, 1972 3,705,913ELECTROPHOTOGRAPHIC SENSITIZERS Charles J. Fox and Arthur L. Johnson,Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. NoDrawing. Original application Mar. 18, 1968, Ser. No.

714,091, now Patent No. 3,589,897. Divided and this application Nov. 27,1970, Ser. No. 93,509 Int. Cl. C07c 87/50, 87/64 US. Cl. 260-391 20Claims ABSTRACT OF THE DISCLOSURE Compounds having the structure aresensitizers for photoconductors in electrophotographic elements.

This application is a division of U.S. Patent application Ser. No.714,091, Novel Electrophotographic Sensitizers, filed Mar. 18, 1968, nowU.'S. Pat. 3,589,897. This application is also a continuation-in-part ofSer. No. 687,503, filed Dec. 4, 1967, now US. Pat. 3,488,705 and Ser.No. 447,937, filed Mar. 16, 1965, now US. Pat. 3,387,973 which is adivision of Ser. No. 163,092, now US. Pat. 3,234,280.

This invention relates to a novel class of organic compounds, theprocess for preparing these novel compounds and to their use assensitizers in electrophotographic elements.

The process of xerography, as disclosed by Carlson in US. 2,297,691,employs an electrophotograpln'c element comprising a support materialbearing a coating of a normally insulating material whose electricalresistance varies with the amount of incident actinic radiation itreceives during an imagewise exposure. The element, commonly termed aphotoconductive element, is first given a uniform surface charge,generally in the dark after a suitable period of dark adaptation. It isthen exposed to a pattern of actinic radiation which has the effect ofdifferentially reducing the potential of the surface charge inaccordance with the relative energy contained in various parts of theradiation pattern. The differential surface charge or electrostaticlatent image remaining on the electrophotographic element is then madevisible by contacting the surface with a suitable electroscopic markingmaterial. Such marking material or toner, whether contained in aninsulating liquid or on a dry carrier, can be deposited on the exposedsurface in accordance with either the charge pattern or in the absenceof charge pattern as desired. The deposited marking material may then beeither permanently fixed to the surface of the sensitive element byknown means such as heat, pressure, solvent vapor, or the like, ortransferred to a second element to which it may similarly be fixed.Likewise, the electrostatic latent image can be transferred to a secondelement and developed there.

Various photoconductive insulating materials have been employed in themanufacture of electrophotographic elements. For example, vapors ofselenium and vapors of selenium alloys deposited on a suitable supportand particles of photoconductive zinc oxide held in a resinous,film-forming binder have found wide application in present-day documentcopying applications.

Since the introduction of electrophotography, a great many organiccompounds have also been screened for their photoconductive properties.As a result a very large number of organic compounds are known topossess some degree of photoconductivity. Many organic compounds haverevealed a useful level of photoconduction and have been incorporatedinto photoconductive compositions. Optically clear organicphotoconductor-containing elements having desirable electrophotographicproperties can be especially useful in electrophotography. Suchelectrophotographic elements maybe exposed through a transparent base ifdesired, thereby providing unusual flexibility in equipment design. Suchcompositions, when coated as a film or layer on a suitable support alsoyield an element which is reusable; that is, it can be used to formsubsequent images after residual toner from prior images has beenremoved by transfer and/ or cleaning.

Although some of the organic photoconductors comprising the materialsdescribed are inherently light sensitive, their degree of sensitivity isusually low and in the short wave length portion of the spectrum so thatit is common practice to add materials to increase the speed and toshift the sensitivity toward the longer wave length portion of thevisible spectrum. Increasing the speed and shifting the sensitivity ofsuch systems into the visible regions of the spectrum has severaladvantages: it makes available inexpensive and convenient light sourcessuch as incandescent lamps; it reduces exposure time; it makes possiblethe recording of a wide range of colors in proper tonal relationship,and allows projection printing through various optical systems. Byincreasing the speed through the use of sensitizers, photoconductorswhich would otherwise have been unsatisfactory are useful in processeswhere high speeds are required such as document copying.

It is, therefore, an object of this invention to provide a novel classof organic compounds useful as sensitizers in combination with organicphotoconductors.

A further object of this invention is to provide a novel process forpreparing these compounds.

Another object of this invention is to provide novel sensitizedphotoconductive elements.

These and other objects of this invention are accomplished by novelcompounds having the following strucn is an integer from 2 to 12;

Ar and Ar, are each aryl radicals, including substituted aryl radicals,such as a phenyl radical, a naphthyl radical, an alkylphenyl radical, ahalophenyl radical, an aminophenyl radical, etc., and

X is a halogen atom, e.g., chlorine, fluorine, bromine, etc. or theanion of an organic acid salt, e..g., an alkanoate radical having one toten carbon atoms such as a formate, acetate, propionate or a butyrateradical including a substituted alkanoate radical such as a haloacetate,cyanoacetate or an oxalate radical; an aryloate radical such as abenzoate or a naphthoate radical and including a substituted aryloateradical such as a salicylate or an anthranilate radical; an alkenoateradical having one to ten carbon atoms such as an acrylate, crotonate orvinylacetate radical; or an aryl or an alkane sulfonate radical such asa benzene sulfonate or a methylsulfonate radical.

These compounds are useful as sensitizers for organic photoconductors inelectrophotographic elements. When they are used in this capacity,substantial increases are noted in the speeds of the elements.

The preferred sensitizers of this invention have the following formula:

Compound No.

CHa--O- OH:ClG-O- VII u cHoh-o-o- VIII (a C CI:CO 1x CHzF-CO x tCHFz-O-D- XI C Fa-C- 0- x11 (III CN-O 111-0-0- xm c H0 0 o-o-o x1v--0.118s o,- v

xvrr

co N ll where n and X are the same as set forth above.

(Formula B) As previously mentioned, these compounds are pre- The novelcompounds of this invention are prepared pared by reacting astoichiometric excess of a carbonyl by reacting a stoichiometric excessof a carbonyl halide having the formula:

0 Y- ("J-Y (Formula C) where Y is a halogen atom, with a triarylaminehaving the formula:

halide such as phosgene with a triarylamine. Since the aryl groups ofthe triarylamine can be substituted, the nature and extent of thissubstitution will be dictated by the type of compound which is desired.Thus, when triphenylamine is used, the ultimate compound prepared hasphenyl radicals which contain no substitution. The employment of4-methyltriphenylamine results in a compound having phenyl groupssubstituted by methyl radicals.

In order to obtain the recurring units depicted in Formula A, it isgenerally necessary to use a stoichiometric excess of the carbonylhalide, i.e., more than one mole of carbonyl halide for three moles oftriarylamine. Thus, the molar ratio of carbonyl halide to triarylamineis suitably 1:2 to 2:1 and preferably 1:1.

The reaction temperature is maintained below 250 C. and preferablybetween 20 C. and 250 C. The reaction is carried out at elevatedpressures between 1.0 and p.s.i.g. When an autoclave is employed,autogenous pressure is sufiicient. The reaction time can vary from a fewminutes to several hours, the preferred times being 0.1 to hours.

The recovery of those compounds in which X is halogen can beaccomplished according to conventional workup techniques. Thus,successive extractions with solvents such as chloroform, diethyl etherand acetone elfectively isolate the various molecular weight fractionsof the compound. In order to prepare the organic acid salt derivatives,the halogen derivative is converted to the corresponding carbinol base.This is accomplished either by continuously washing the material withwater or by treating it with dilute alkali. The appropriate organic acidis then added to the carbinol base and the organic acid salt derivativerecovered according to conventional techniques.

Electrophotographic elements of the invention can be prepared with anyorganic photoconductive compound and the novel sensitizing compounds ofthis invention in the usual manner, i.e., by blending a dispersion orsolution of the photoconductive compound together with a binder, whennecessary or desirable, and coating or forming a self-supporting layerwith the photoconductive composition. Generally, a suitable amount ofthe sensitizing compound is mixed with the photoconductive coatingcomposition so that, after thorough mixing, the sensitizing compound isuniformly distributed throughout the desired layer of the coatedelement. The amount of sensitizer that can be added to aphotoconductor-incorporating layer to give effective increases in speedcan vary widely. The optimum concentration in any given case will varywith the specific photoconductor and sensitizing compound used. Ingeneral, substantial speed gains can be obtained where an appropriatesensitizer is added in a concentration range from about 0.0001 to about30 percent by weight based on the weight of the film-forming coatingcomposition. Normally, a sensitizer is added to the coating compositionin an amount from about 0.005 to about 5.0 percent by weight of thetotal coating composition.

The sensitizers of this invention are effective for enhancing theelectrophotosensitivity of a wide variety of photoconductors. Thepreferred photoconductors are those organic compounds which exhibit anelectrophotosensitivity to light and are capable of forming transparentelements. An especially useful class of organic photoconductors isreferred to herein as organic amine photoconductors. Such organicphotoconductors have as a common structural feature at least one aminogroup. Useful organic photoconductors which can be spectrally sensitizedin accordance with this invention include, therefore, arylaminecompounds comprising (1) diarylamines such diphenylamine,

dinaphthylamine,

-N,N'-diphenylbenzidine, N-phenyl-l-naphthylamine;N-phenyl-Z-naphthylamine; N,'-diphenyl-p-phenylenediamine;Z-carboxy-S-chloro-4-methoxydiphenylamine; p-anilinophenol;N,N'-di-2-naphthyl-p-phenylenediamine;

those described in Fox US. Patent 3,240,597 issued March 15, 1966, andthe like, and (2) triarylamines 1ncluding (a) nonpolymerictriarylamines, such as triphenylamine,N,N,N,N-tetraphenyl-m-phenylenediamine; 4-acetyltriphenylamine,4-hexanoyltriphenylamine; 4-lauroyltriphenylamine;4-hexyltriphenylamine, 4-dodecyltriphenylamine,4,4-bis(diphenylamino)benzil, 4,4'-'bis(diphenylamino)benzophenone,

and the like, and (b) polymeric triarylamines such as poly[N,4"-(N,N,N-triphenylbenzidine) polyadipyltriphenylamine,polysebacyltriphenylamine; polydecamethylenetriphenylamine;poly-N-(4-vinylphenyl)diphenylamine,poly-N-vinylphenyl)-a,ot'-dinaphthylamine and the like. Other usefulamine-type photoconductors are disclosed in US. Pat. 3,180,730 issuedApr. 27, 1965. In addition, photoconductive substances capable of beingspectrally sensitized in accordance with this invention are disclosed inFox US. Pat. 3,265,496 issued Aug. 9, 1966, and include thoserepresented by the following general formula:

wherein A represents a mononuclear or polynuclear divalent aromaticradical, either fused or linear (e.g., phenyl, naphthyl, biphenyl,binaphthyl, etc.), or a substituted divalent aromatic radical of thesetypes wherein said substituent can comprise a member such as an acylgroup having from 1 to about 6 carbon atoms (e.g., acetyl, propionyl,butyryl, etc.), an alkyl group having from 1 to about 6 carbon atoms(e.g., methyl, ethyl, propyl, butyl, etc.), an alkoxy group having from1 to about 6 carbon atoms (e.g., methoxy, ethoxy, propoxy, pentoxy,etc.), or a nitro group; A represents a mononuclear or polynuclearmonovalent aromatic radical, either fused or linear (e.g., phenyl,naphthyl, biphenyl, etc.); or a substituted monovalent aromatic radicalwherein said substituent can comprise a member, such as an acyl grouphaving from 1 to about 6 carbon atoms (e.g., acetyl, propionyl, butyryl,etc.), an alkyl group having from 1 to about 6 carbon atoms (e.g.,methyl, ethyl, propyl, butyl, etc.), an alkoxy group having from 1 toabout 6 carbon atoms (e.g., methoxy, propoxy, pentoxy, etc.), or a nitrogroup; Q can represent a hydrogen atom, a halogen atom or an aromaticamino group, such as ANH-; b represents an integer from 1 to about 12,and G represents a hydrogen atom, a mononuclear or polynuclear aromaticradical, either fused or linear (e.g., phenyl, naphthyl, biphenyl,etc.), a substituted aromatic radical wherein said substituent comprisesan alkyl group, an alkoxy group, an acyl group, or a nitro group, or apoly(4-vinylphenyl) group which is bonded to the nitrogen atom by acarbon atom of the phenyl group.

Polyarylalkane photoconductors are particularly useful in producing thepresent invention. Such photoconductors are described in US. Pat.3,274,000; French Pat. 1,383,- 461 and in copending application of Seusand Goldman entitled Photoconductive Elements Containing OrganicPhotoconductors filed Apr. 3, 1967. These photoconductors include leucobases of diaryl or triarylmethane dye salts, 1,1,1-triarylalkaneswherein the alkane moiety has at least two carbon atoms andtetraarylmethanes, there being substituted an amine group on at leastone of the aryl groups attached to the alkane and methane moieties ofthe latter two classes of photoconductors which are non-leuco basematerials.

Preferred polyaryl alkane photoconductors can be represented by theformula:

wherein each of D, E and G is an aryl group and J is a hydrogen atom, analkyl group, or an aryl group, at least one of D, E and G containing anamino substituent. The aryl groups attached to the central carbon atomare 7 preferably phenyl groups, although naphthyl groups can also beused. Such aryl groups can contain such substituents as alkyl and alkoxytypically having 1 to 8 carbon atoms, hydroxy, halogen, etc. in theortho, meta or para positions, ortho-substituted phenyl being preferred.The aryl groups can also be joined together or cyclized to form afluorene moiety, for example. The amino substituent can be representedby the formula wherein each L can be an alkyl group typically having 1to 8 carbon atoms, a hydrogen atom, an aryl group, or together thenecessary atoms to form a heterocyclic amino group typically having 5 to6 atoms in the ring such as morpholino, pyridyl, pyrryl, etc. At leastone of D, E, and G is preferably p-dialkylaminophenyl group. When I isan alkyl group, such an alkyl group more generally has 1 to 7 carbonatoms.

Representative useful polyarylalkane photoconductors include thecompounds listed below:

methane.

(10). 4Z4" klixiswimethylamino)-2',2"-dlmethyl-4-methoxytripheny1- meone.

Bis(4-diethylamlno) -1,1,1-triphenylethane.

(l Bis(4-diethylamino)tetraphenylmethane.

(l3) 4',4"-bis(benzylethylamlno)-2,2"-dlmethyltriphenylmethane. (14)4',4"-bis (diethylamino)-2',2"-diethoxytrlphenylmethaue.

(15) fl-bis (dimethylarnino) -1,1,1-triphenylethane.

(16) 1-(4-N,N-d1methylamlnophenyl) -1,1-diphenylethaue. (17)4-dimethylaminotetraphenylmethane.

(l8) s-diethylaminctetrephenylmethane.

Additional organic photoconductors which can be employed with thesensitizing compounds described herein are non-ionic cycloheptenylcompounds such as those described in copending application Ser. No.654,091, tiled July 18, 1967; the N,N-bicarbazyls and tetra-substitutedhydrazines; the 3,3'-bis-1,5-diarylpyrazolines; triarylamines having atleast one of the aryl radicals substituted by either a vinyl radical, ora vinylene radical having at least one active hydrogen-containing groupsuch as pdiphenylaminocinnamic acid; triarylamines substituted by anactive hydrogen-containing group, e.g., 4-carboxytriphenylarnine; andthose described in Australian Pat. 248,- 402. Other organicphotoconductors that can be sensitized in accordance with the inventioninclude organo-metallic compounds which are the organic derivatives ofGroup Na and Va metals such as those having at least one aminoaryl groupattached to the metal atom as described in Ser. No. 650,664 filed July3, 1967. Exemplary organometallic compounds are thetriphenyl-p-dialkylaminophenyl derivatives of silicon, germanium, tinand lead and the tri-p-dialkylaminophenyl derivatives of arsenic,antimony, phosphorous and bismuth.

Another class of photoconductors useful in this invention are the4-diarylamino-substituted chalcones. Typical compounds of this type arelow molecular weight nonpolymeric ketones having the general formula:

wherein R, and R are each phenyl radicals including substituted phenylradicals and particularly when R: is a. phenyl radical having theformula:

where R and R, are each aryl radicals, aliphatic residues of l to 12carbon atoms such as alkyl radicals preferably having 1 to 4 carbonatoms or hydrogen. Particularly advantageous results are obtained when Ris a phenyl radical including substituted phenyl radicals and where R:is diphenylamino, dimethylamino or hydrogen.

Preferred binders for use in preparing the present photoconductivelayers comprise polymers having fairly high dielectric strength whichare good electrically insulating film-forming vehicles. Materials ofthis type comprise styrene-butadiene copolymers; silicone resins;styrenealkyd resins; silicone-alkyd resins; soya-a'lkyd resins; poly(vinyl chloride); poly(vinylidene chloride); vinylidenechloride-acrylonitrile copolymers; poly(vinyl acetate); vinylacetate-vinyl chloride copolymers; poly(vinyl acetals), such aspoly(vinyl butyral); polyacrylic and methacrylic esters, such aspoly(methylmethacrylate), po1y(nbutylmethacrylate), poly(isobutylmethacry'late), etc.; polystyrene; nitrated polystyrene;polymethylstyrene; isobutylene polymers; polyesters, such aspoly(ethylenealkaryloxyalkylene terephthalate); phenol-formaldehyderesins; ketone resins; polyamides; polycarbonates; polythiocarbonates;poly (ethyleneglycol-co-bishydroxyethoxyphenyl propane terephthalate);nuclear substituted polyvinyl haloarylates; etc. Methods of makingresins of this type have been described in the prior art, for example,styrene-alkyd resins can be prepared according to the method describedin U.S. Pats. 2,361,019 and 2,258,423. Suitable resins of the typecontemplated for use in the photoconductive layers of the invention aresold under such trade names as Vitel PE-lOl, Cymac, Piccopale 100, SaranF- 220 and Lexan 105. Other types of binders which can be used in thephotoconductive layers of the invention include such materials asparafiin, mineral waxes, etc.

Solvents of choice for preparing coating compositions of the presentinvention can include a number of solvents such as benzene, toluene,acetone, Z-butanone, chlorinated hydrocarbons, e.g., methylene chloride,ethylene chloride, etc., ethers e.g., tetrahydrofuran, or mixtures ofthese solvents, etc.

In preparing the coating composition useful results are obtained wherethe photoconductor substance is present in an amount equal to at leastabout 1 weight percent of the coating composition. The upper limit inthe amount of photoconductor substance present can be widely varied inaccordance with usual practice. In those cases where a binder isemployed it is normally required that the photoconductor substance bepresent in an amount from about 1 weight percent of the coatingcomposition to about 99 weight percent of the coating composition. Apreferred weight range for the photoconductor substance in the coatingcomposition is from about 10 weight percent to about 60 weight percent.

Coating thicknesses of the photoconductive composition on a support canvary widely. Normally, a coating in the range of about 0.001 inch toabout 0.01 inch before drying is useful for the practice of thisinvention.

The preferred range of coating thickness was found to be in the rangefrom about 0.002 inch to about 0.006 inch before drying although usefulresults can be obtained outside of this range.

Suitable supporting materials for coating the photoconductive layers ofthe present invention can include any of a wide variety of electricallyconducting supports, for example, paper (at a relative humidity above 20percent); aluminum-paper laminates; metal foils such as aluminum foil,zinc foil, etc.; metal plates, such as aluminum, copper, zinc, brass,and galvanized plates; vapor deposited metal layers such as silver,nickel, aluminum and the like coated on paper or conventionalphotographic film bases. An especially useful conducting support can beprepared by coating a support material such as polyethyleneterephthalate with a layer containing a semiconductor dispersed in aresin. Such conducting layers both with and without insulating barrierlayers are described in US. Pat. 3,245,- 833. Likewise, a suitableconducting coating can be prepared from the sodium salt of acarboxyester lactone of maleic anhydride and a vinyl acetate polymer.Such kinds of conducting layers and methods for their optimumpreparation and use are disclosed in US. 3,007,901 and 3,267,807.

The elements of the present invention can be employed in any of thewell-known electrophotographic processes which require photoconductivelayers. One such process is the aforementioned xerographic process. Asexplained previously, in a process of this type the electrophotographicelement is given a blanket electrostatic charge by placing the sameunder a corona discharge which serves to give a uniform charge to thesurface of the photoconductive layer. This charge is retained by thelayer owing to the substantial insulating property of the layer, i.e.,the low conductivity of the layer in the dark. The electrostatic chargeformed on the surface of the photoconducting layer is then selectivelydissipated from the surface of the layer by exposure to light through animage-bearing transparency by a conventional exposure operation such as,for example, by contact-printing technique, or by lens projection of animage, etc., to form a latent image in the photoconducting layer. Byexposure of the surface in this manner, a charged pattern is created byvirtue of the fact that light causes the charge to be con- 10 in the artand have been described in a number of US. and foreign patents, such asUS. Pats. 2,297,691 and 2,551,582, and in RCA Review," vol. 15 (1954),pages 469-484.

The present invention is not limited to any particular mode of use ofthe new electrophotographic materials, and the exposure technique, thecharging method, the transfer (if any), the developing method, and thefixing method as well as the material used in these methods can beselected and adapted to the requirements of any partic ular technique.

Electrophotographic materials according to the present invention can beapplied to reproduction techniques wherein difierent kinds ofradiations, i.e., electromagnetic radiations as well as nuclearradiations, can be used. For this reason, it is pointed out herein thatalthough materials according to invention are mainly intended for use inconnection with methods comprising an exposure, the termelectrophotography wherever appearing in the description and the claims,is to be interpreted broadly and understood to comprise both xerographyand xeroradiography.

The following examples are included for a further understanding of theinvention.

EXAMPLE 1 Preparation of Compound I A mixture of 29.4 grams oftriphenylamine and 12 grams of liquid phosgene are heated in a sealedautoclave at 200 C. for 4 hours with agitation. At the end of thisperiod the autoclave is cooled and the crude solid product is dissolvedin 100 ml. of chloroform. The remaining insoluble material is filteredand the mother liquor containing soluble product is sepaarted intofractions in the manner set forth below. The chloroform solution isadded to two liters of ether causing the coprecipitation of fractions Cand D. The coprecipitate is filtered and washed. Fraction B is isolatedby evaporation of the solvent from the filtrate. The fraction containingC and D combined is extracted with acetone to provide theacetone-soluble fraction D and the acetone-insoluble fraction C whichremains as the residue. These fractions are fully described in thefollowing Table II.

TABLE II Elemental analysis M.P Fraction Solubility C H N Cl IVLW.

B Soluble diethyl ether 84.3 5.7 5.2 3.2 458 75 C Soluble chloroform;Insoluble acetone; Insoluble ether... 82.4 5.5 4.8 2.7 4, 600 275 DSoluble acetone; Insoluble diethyl ether 80.6 5.5 4.6 6.9 1,050 210ducted away in proportion to the intensity of the illumi- EXAMPLE 2nation in a particular area. The charge pattern remaining after exposureis then developed, i.e., rendered visible, by treatment with a mediumcomprising electrostatically attractable particles having opticaldensity. The developing electrostatically attractable particles can thein the form of a dust, e.g., powder, a pigment in a resinous carrier,i.e., toner, or a liquid developer may be used in which the developingparticles are carried in an electrically insulating liquid carrier.Methods of development of this type are widely known and have beendescribed in the patent literature in such patents, for example, as US.2,297,691 and in Australian Pat. 212,315. In processes ofelectrophotographic reproduction such as in xerography, by selecting adeveloping particle which has as one of its components, a low-meltingresin, it is possible to treat the developed photoconductive materialwith heat and cause the powder to adhere permanently to the surface ofthe photoconductive layer. In other cases, a transfer of the imageformed on the photoconductive layer can be made to a second support,which would then become the final print. Techniques of the typeindicated are well known Preparation of Compounds II and III CompoundsII and III are prepared in the same manner as Compound I except thatcarbonyl fluoride and carbonyl bromide are used as starting materialsinstead of phosgene. Good yields of both products are obtained.

EXAMPLE 3 Preparation of Compound XI EXAMPLE 4 Preparation of CompoundsIV-X and XII-XVII 1 1 These compounds are all prepared in the mannerdescribed in Example 3 using the following acids in place of thetrifiuoroacetic acid:

TABLE HI Acid V Acetic.

VI- Chloroacettc. VII Dlchloroacetic. VIII- Trichloroncetic. IX---Fluoroacetlc. X- Dlfiuoroacetlc. XIL- Cyanoecetie. XIII- Oxallc.

XIV- Phenylsulionlc. XV Methylsulionic. XVI Salicylic. XVIIDiphenylanthranillc.

Good yields are obtained in each instance.

EXAMPLE 5 The photoconductor is 1,3,S-triphenyl-Z-pyrazoline, thesolvent is dichloromethane, the sensitizer is Compound I and the binderis Vitel 101, a polyester of terephthalic acid and a mixture of ethyleneglycol (1 part by weight) and 2,2-bis[4-(B-hydroxyethoxy)phenyl]propane(9 parts by weight) manufactured by Goodyear Tire and Rubber Co. Theresulting dope is then coated at 0.004 inch thickness on the aluminumsurface of a paper-backed aluminum foil at 110 F. The coating isconcurrently dark conditioned and cured at 47 C. for 15 hours. Thesample is charged positively under a corona discharge unit to 600 voltsabove ground potential. The charged element is then exposed for 3seconds through a step tablet to a tungsten source at 3000 K. and of191-1 foot candle intensity at the point of exposure. The step tabletconsists of 0.1 log E corona charger. The layer is then covered with atransparent sheet bearing a pattern of opaque and light transmittingareas and exposed to the radiation from an incandescent lamp with anillumination intensity of about 19:1 foot candles for 3 seconds. Theresulting electrostatic latent image is developed in the usual manner bycascading over the surface of the layer a mixture of negatively chargedblack thermoplastic toner particles and glass beads. A good reproductionof the pattern results in each instance.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be eifected within the spirit and scopeof the invention as described hereinabove and as defined in the appendedclaims.

We claim:

I. A compound having the formula:

wherein n is an integer from 2 to 12; X is a halogen or an anion of anorganic acid salt selected from the group consisting of an alkanoatehaving one to ten carbon atoms, a haloalkanoate having one to ten carbonatoms, a cyanoalkanoate having one to ten carbon atoms, an alkenoatehaving one to ten carbon atoms, a benzoate, a naphthoate, a benzenesulfonate, an alkane sulfonate, an oxalate, a salicylate, and ananthranilate; and Ar and Ar: are each aryl radicals selected from thegroup consisting of phenyl radicals, naphthyl radicals, alkylphenylradicals, halophenyl radicals, and aminophenyl radicals.

2. The compound of claim 1 wherein X is chlorine or an anion of anorganic acid salt selected from the group consisting of an alkanoate, achloroalkanoate, a benzoate, a naphthoate, an alkenoate, a benzenesulfonate, and a methyl sulfonate.

3. A compound having the formula:

EXAMPLE 6 Coating compositions containing the sensitizing compounds ofthis invention are prepared and coated in the manner described inExample 5. In a darkened room, the surface of each of thephotoconductive layers so prepared is charged to a potential of about+600 volts under a wherein n is an integer from 2 to 12 and X is ahalogen atom or an anion of an organic acid salt selected from the groupconsisting of a formate anion, an acetate anion, a salicylate anion, ananthranilate anion, an oxalate radical, a benzene sulionate anion, analkane sulfonate anion, and a malonate anion.

4. The compound of claim 3 wherein X is a chlorine atom.

5. The compound of claim 3 wherein X is a bromine atom.

6. The compound of claim 3 wherein X is an acetate amon.

7. The compound of claim 3 wherein X is a fluorine atom.

14 8. The compound of claim 3 wherein X is a chloro- 18. The compound ofclaim 3 wherein X is a monoacetate anion. formate anion.

9. The compound of claim 3 wherein X is a dichloro- 19. The compound ofclaim 3 wherein X is a diphenylacetate anion. anthranilate anion.

10. The compound of claim 3 wherein X is a fluoro- 5 20. A compoundhaving the formula:

-DrQ' G- -Q 11. The compound of claim 3 wherein X is a difluoro- 20whereinn is an integer from 2 to 12. acetate anion.

12. The compound of claim 3 wherein X is a trifluoro- References Citedacetate anion. d l h UNITED STATES PATENTS 13. The compoun at 0 mm 3 werem X 1s a cyanO- 290,856 12/1883 Caro 260 391 l i lh e m ound of claim3 wherein X is a salic late 25 327953 10/1885 Kern et a1 260391 P y3,114,726 12/1963 Conger et a1 260391 15. The compound of claim 3wherein X is an oxalate 3046209 7/1962 260-391 anion 2,448,823 9/1948Popkln 260--391 16. The compound of claim 3 wherein X is a benzene- 30sulfonate anion VIVIAN GARNER, Primary Examiner 17. The compound ofclaim 3 wherein X is a methyl- US. Cl. X.R.

sulfonate anion. 96-15, 1.6

